Bacteriological media tube

ABSTRACT

A TRANSPARENT TEST TUBE IS PROVIDED WITH A CONSTRICTION WHICH PERMITS THE TUBE TO BE FILLED WITH TWO UNLIKE MEDIA SEPARATED BY A GAS BUBBLE. THE CONSTRICTION IS PROVIDED WITH AN ARCUATE SHAPE WHICH PERMITS FILLING OF THE LOWER PORTION OF THE ESCAPE CONFINED GAS WITH A CONSTRICTION SMALL ENOUGH TO LIMIT THE FLOW FROM THE UPPER PORTION TO THE LOWER PORTION DURING THE FILLING OPERATION.

20, 174 o. A. BECKFORD 3,830,702

BACTERIOLOGICAL MEDIA TUBE Filed Feb. 2. 1973 United States Patent3,830,702 BACTERIOLOGICAL MEDIA TUBE Orville A. Beckford, PortWashington, N.Y., assignor to Diagnostic Research, Inc., Roslyn, N.Y.Filed Feb. 2, 1973, Ser. No. 329,014 Int. Cl. C12k 1/10 U.S. Cl. 195-1393 Claims ABSTRACT OF THE DISCLOSURE A transparent test tube is providedwith a constriction which permits the tube to be filled with two unlikemedia separated by a gas bubble. The constriction is provided with anarcuate shape 'which permits filling of the lower portion of the escapeconfined gas with a constriction small enough to limit the flow from theupper portion to the lower portion during the filling operation.

This invention relates to transparent tubes containing bacteriologicalmedia.

BACKGROUND OF THE INVENTION It is known to employ tubes containing mediafor providing biochemical reactions for the purpose of identifyingvarious species of bacteria. For example, test for phenylalaninedeaminese, H 8 production, indole, lysine decarboxylation, ornithinedecarboxylation, motility, lactose fermentation and glucose fermentationare combined in such a manner that in the presence of individual speciesof enterobacteriaceae the media takes on a particular characteristicappearance.

It has been found that by putting a constriction in the tube betweenmedia designed for aerobic and anerobic bacteria, clearer, sharpercolors and improved shelf life is obtained. However, the size and shapeof the constrictions have been found to be critical during the fillingoperation. For example, if the opening is too large, the upper layers ofmedia will mix with the lower layer and not provide for isolation. Iftoo small, air tends to be trapped in the lower media causing bubbles toform as the media cools from the warm state, which it is initiallyintroduced in, to the gel state. Accordingly, it is an object of thisinvention to provide an improved constricted tube.

SUMMARY OF THE INVENTION A transparent test tube is provided with aconstricted orifice having an arcuate shape which, in cross section,resembles a pair of opposed hyperbolas. The tube is filled with twodifferent test media separated by a gas bubble in the orifice area.

DESCRIPTION OF THE DMWINGS In the various figures of the drawing likeparts designate like figures of the drawing.

In the drawing:

FIG. 1 is a view taken in elevation of a media tube;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 2; and

FIG. 5 is a view taken in elevation of the tube of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, inFIG. 1 there is shown a transparent test tube which may be made of glassor 3,830,702 Patented Aug. 20, 1974 suitable plastic which is providedwith a constricted area 12. The constriction provides an opening 14(FIG. 2') and as is shown in FIG. 4, is defined by two arcuate portions15 and 16 which resemble hyperbolas, although they need notmathematically follow the hyperbola equation and may be, for example,elliptical. Other arcuate shapes may be employed.

Dimension a is typically 2 mm.:0.4 mm., while dimension b is typically 1mm. The overall length of the arcuate portion should be about 4 mm. Thecompleted tube is shown in FIG. 5. Tube 10 is provided with media 18 and20 and is provided with a closure member 22. The closure member may be astopper or a tight fitting plastic cap 22 as shown in FIG. 5.

Typically, media in a liquid state would be injected into the lowerportion by means of a needle extending through opening 14. It has beenfound that with the arcuate shape, trapped air is readily forced pastthe needle into the atmosphere. After the lower portion is filled, theupper portion is filled with media in liquid form. The media is usuallyan agar based composition containing test media. When heated the agarmedia is quite fluid and is readily introduced into the tube. On theother hand, upon cooling the agar media congeals.

One application of the tube is disclosed in applicants copendingapplication filed concurrently entitled Enteric Bascilli DifferentialApparatus, Ser. No. 329,176.

Various other configurations and dimensions for the constricted portionwere tested and found to be characterized by a high reject rate. Onecause for rejection was the formation of bubbles which were captured bythe gelling media. With the introduction of the present configuration,rejections for this reason have become nil.

These and other objects, features and advantages of the invention will,in part, be pointed out with particularity and will, in part, becomeobvious from the following more detailed description of the inventiontaken in conjunction with the accompanying drawing which forms anintegral part thereof.

What I claim as new and desire to secure by Letters Patent is:

1. A bacterial medium tube comprising:

(a) an elongated transparent tube having a lower compartment of a firstcross-sectional area and an upper compartment of substantially the samecross-sectional area and a conduit extending from the said upper to thesaid lower chamber, said conduit being defined by walls continuouslytapering inwardly from each of said chambers defining an orifice havinga traverse dimension between 1.6 mm. and 2.4 mm.

(b) a first medium in said lower compartment;

(c) a second medium in said upper compartment different than that ofsaid first medium;

(d) a gas in said conduit separating said first and said second medium.

2. The tube of Claim 1 formed of glass.

3. The tube of Claim 1 formed of plastic.

References Cited UNITED STATES PATENTS 3,750,645 8/1973 Bennett et al.23-292 X A. LOUIS MONACELL, Primary Examiner R. J. WARDEN, AssistantExaminer U.S. Cl. X.R. l54, 103.5 R

